Water temperature has a major influence on the host innate immune defence and the infectivity of pathogens in ectothermic teleosts. Toll‐like receptors (TLRs) are the first and well‐characterized innate immune receptors that are conserved in vertebrates. However, little is known about the effect of temperature variation on TLRs in fish species. In this study, we used adult zebrafish as a research model to investigate the effect of water temperature on TLRs. Whole genome searches identified 20 TLR homologue genes in zebrafish. Multiple sequence alignment and protein structure analysis revealed the conserved domains for these TLR proteins. To identify TLR genes related to temperature variation, TLR family genes from 12 species with different body temperatures were assigned to conduct phylogenetic analyses. Based on the phylogenetic relationships, TLR3, TLR4, TLR5 and TLR20~21 were selected as candidate genes. Immunostimulation data indicated that TLR3, TLR5, and TLR21 were more sensitive to temperature variation and their expression levels were affected in response to pathogen stimulation. Taken together, our results provide a new opportunity to understand the roles of temperature on host innate immune response in fishes and have broader implications for disease prevention in aquaculture.

中文翻译：

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斑马鱼Toll样受体的全基因组分析以及温度升高对受激病原体感染的响应

水温对宿主先天性免疫防御以及外热硬骨鱼中病原体的传染性具有重要影响。Toll样受体（TLR）是脊椎动物中第一个且特征明确的先天免疫受体。但是，关于温度变化对鱼类中TLR的影响知之甚少。在这项研究中，我们使用成年斑马鱼作为研究模型来研究水温对TLR的影响。全基因组搜索确定了斑马鱼中的20个TLR同源基因。多个序列比对和蛋白质结构分析揭示了这些TLR蛋白质的保守结构域。为了鉴定与温度变化有关的TLR基因，TLR分配了来自12个物种的不同体温的家族基因进行系统发育分析。根据系统发育关系，选择TLR3，TLR4，TLR5和TLR20〜21作为候选基因。免疫刺激数据表明TLR3，TLR5，和TLR21是对温度变化更敏感，它们的表达水平响应于病原体刺激受影响。综上所述，我们的结果为了解温度对鱼类宿主固有免疫反应的作用提供了新的机会，并且对水产养殖疾病的预防具有更广泛的意义。